We don't target low end devices anymore so there's no resource issues to worry about.
Tested by opening http://www.itisatrap.org/firefox/its-an-attack.html We get a nice error page explaining how bad this page is.
Created attachment 8688097 [details] [diff] [review] default-safebrowsing.patch
What changed since bug 1180503?
iirc François was saying that turning on safebrowsing could cost ~ 3MB, and at the time we still had to support 256MB configuration. This is not the case anymore so I think it's fine to turn on by default. It's easy enough to disable on a per-device basis if we need to.
This doesn't download stuff while on a mobile data connection?